Room thermostat



July 15, 1941. B. E. SHAW ROOM THERMOSTAT Filed May 13, 1940 INVENTOR. fiarzozz/fifiaw, 9.

ATTORNEYS.

Patented July 15, 1941 ROOM THERMOSTAT Burton E. Shaw, Bristol, Ind., assignor to Penn Electric Switch 00., Goshen, Ind., a. corporation of Iowa Application May 13, 1940, Serial No. 334,872

2 Claims.

My present invention relates to a thermostat such as a room thermostat or the like, provided with means to positively retain the switch contacts of the thermostat in open circuit or off position when the range adjusting dial of the thermostat is rotated to a predetermined position.

One object of the invention is to provide means to open the circuit through a room thermostat, which means is simple and inexpensive to install on a room thermostat of the usual construction and which utilizes the range adjusting dial thereof as a means to render the circuit opening means effective without the necessity of having an independent switch for this purpose.

A further object is to provide, in a room thermostat having a cam adjusted range mechanism, a bracket secured to a bimetal supporting arm in such manner that it coacts with the switch arm when the cam is adjusted to a predetermined position and positively holds the switch arm against movement to contact closing position.

With these and other objects in View, my invention consists in the construction, arrangement and combination of the various parts of my device whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in the accompanying drawing. Although the invention is susceptible of a variety of embodiments, it is unnecessary to fully describe and illustrate more than one in order to give a full understanding of the invention both from its structural and functional standpoints. Accordingly, I have illustrated a preferred and desirable embodiment of the invention in the accompanying drawing, in which:

Figure 1 is a front elevation of a room thermostat embodying my invention and with the cover removed, with the exception of a small portion thereof indicated in section;

Figure 2 is a side elevation from the left side of Figure 1 showing the cover in position and sectioned, and

Figure 3 is a view similar to Figure 1 showing the thermostat adjusted to off position.

On the accompanying drawing I have used the reference character B to indicate a base, and C a casing detachably mounted thereon. The casing C supports the usual thermometer tube l and may be secured in position by a screw l2.

A pivot screw l3 extends outwardly from the base B and pivoted thereon is a supporting arm A having a short arm l4 and a long arm l5 connected together by a cross arm IS. The arms M and I5 are perforated to receive the screw l3 so that the arm A is pivotally mounted with respect to the base.

The arm A carries a coiled bimetal element ll which may be secured to the cross bar l6 as by rivets l8. The bimetal element 5 terminates in a straight portion I9 which, together with an arm 20, serves as a switch arm. The portions l9 and 20 are connected together by a screw 2 I.

A stationary contact 22 is mounted in a bracket 23 secured to the base B and a movable contact 24 is adapted to coact therewith. The contact 24 is carried by a leaf spring 25 secured to the switch arm l920 by the screw 2i. The arm 20 has an armature portion 26 adapted to coact with a permanent magnet 21 for producing snap action of the switch.

An adjusting dial 28 is rotatably mounted on a screw 3!] extending from the base B. The dial 28 has indicia which cooperate with a pointer 29 from the casing C to indicate the various temperatures to which the adjusting dial may be adjusted.

The dial 28 carries a cam 30 coactable with an adjusting screw 3| of the arm A. The screw 3| is threaded in a split flange 32 of the arm.

A spring 33 is coiled around the pivot screw l3 and has a hook end 34 engaging the arm IS. The spring 33 also has a terminal end 35 embedded in a socket 36 in the base B. The spring 33 biases the adjusting screw 3| to contact with the cam 30 in all positions of adjustment of the cam.

A bracket 31 is secured as by rivets 38 to another arm 39 extending laterally from the arm l4 of the supporting arm A. The bracket 37 carries in a split flange 40 thereof an adjusting screw 4|. The arm 33 is electrically connected with a terminal 42 by a pigtail connection 43 and a screw 44.

Practical operation .throughout the West Coast of the United States. .Heretofore it has been customary to provide a toggle switch in series with the room thermostat for the purpose of shutting oif the burner at night. I have however provided, by means of a simple bracket 31, mechanism whereby a positive shut-off of the room thermostat may be effected at night.

The dial 28 is adjustable through a range of movement determined by an arcuate slot 45 therein and a stop lug 46 extending upwardly from the base B. When the dial 28 is adjusted to one of its limits of movement, as shown in Figure 3, the pointer 29 indicates 01f. In this position, the adjusting screw 4| has contacted the switch arm I9 and, it will be noted, holds the contact 24 separated from the contact 22. This condition obtains in spite of any reduction in ambient temperature tending to close the switch. When the dial 28 is rotated slightly clockwise, however, the screw is positioned where it permits free actuation of the switch contacts in response to temperature changes affecting the bimetal element H, and any adjustment for a temperature higher than 56 likewise results in the thermostat operating in the normal manner.

The adjusting screw 3| is adjusted at the :fac tory for obtaining the desired switch action at the proper temperature indicated on the dial 28. Thereafter, the set screw may be locked with cement or sealing wax. The set screw 4| is provided in order to permit accurate adjustment, so that the switch will be held in Off position only when the dial 28 is rotated to such indicated position. The screw 4| likewise may thereafter 3 be locked by cement or sealing wax.

By mounting the bracket 31 on the mounting arm A, it is obvious that I have provided a very simple means of assuring an Off condition in the thermostat by movement of the cam 3|] to a predetermined position. The bracket 3'! in no way interferes with the operation of the bimetal element except at the Off position of the adjusting dial.

Having described one specific embodiment of my invention together with the operation thereof, I desire it to be understood that this form is selected merely for the purpose of facilitating disclosure of the invention rather than for the purpose of limiting the number of forms which it mayassume. It is to be further understood that various modifications, adaptations and alterations may be applied to the specific form disclosed to meet the requirements of practice without in any manner departing from the spirit and scope of the present invention except as set forth in the claims appended hereto.

I claim as my invention and desire to secure by Letters Patent of the United States:

1. In a room thermostat, a supporting arm having a perforation for pivotally mounting the arm, said arm having an extension parallel to the pivot axis and terminating in a portion across the pivot axis having a second perforation for pivotally mounting said arm and aligning it at right angles to the pivot axis, a temperature responsive element mounted on said extension of said supporting arm, a switch arm carried by said temperature responsive element, switch contacts under control of said switch arm, a cam for pivotally adjusting said supporting arm and thereby said temperature responsive element, means biasing said supporting arm toward said cam, and a bracket carried by said supporting arm and engageable with said switch arm at one limit of movement of said cam, said bracket being effective to limit the movement of said supporting arm to 'a position retaining said contacts in a predetermined position relative to each other.

2. In a thermostat of the character disclosed, a base, a supporting arm pivotally mounted thereon, an adjusting screw carried by said supporting arm, a cam rotatable on said base, a spring biasing said adjusting screw to engage said cam, a coiled bimetallic element mounted on said supporting arm and carrying a switch arm, switch contacts controlled by said switch arm, and means carried by said supporting arm and having an adjusting screw coactable with said switch arm to hold the same in a predetermined circuit position when said cam is adjusted to one limit of its movement.

BURTON E. SHAW. 

